An optical deflector for use in an image forming apparatus such as a color printer includes a drive motor having a rotary shaft, a polygonal mirror provided on the rotary shaft in an integrally rotatable manner, a substrate on which an electronic component such as a driver IC for controlling drive of the drive motor is mounted, and a cover covering the polygonal mirror, the drive motor and the substrate. In the cover, a region for allowing entering and exiting of a light flux therethrough is provided with a window, and a region covering the polygonal mirror and a region covering the electronic component are provided, respectively, with an air suction hole and an air discharge hole.
In the above optical deflector, upon rotation of the polygonal mirror, air located outside the cover is sucked inside the cover through the air suction hole and then discharged outside the cover through the air discharge hole. By such an airflow flowing from the air suction hole toward the air discharge hole, the electronic component such as a driver IC undergoing heat generation along with the rotation of the polygonal mirror is cooled.